Thermoelectric (TE) energy conversion technology, for power generation based on the Seebeck effect and refrigeration based on Peltier effect, has played an important role in powering deep space missions and cooling sensitive electronics. Without any emission or moving parts, this technology is often considered in the search for sustainable energy sources, with automotive waste heat recovery being of prime interest.
The challenge for thermoelectrics relative to other technologies is the low efficiency of the material. The maximum TE efficiency of a material is characterized by the figure of merit, zT=S2σT/(KE+KL), where S, σ, KE and KL are the Seebeck coefficient, electrical conductivity, and the electronic and lattice components of the thermal conductivity, respectively. State-of-art commercial materials have a peak zT significantly less than unity. So far, only PbTe based materials with peak zT of less than 0.8 have been used in commercial products for power generation in the 250 C-450 C temperature range. Thus, there is a need in the art for improved thermoelectric materials.